Escapement mechanism



J y 1951 G. E. NICHOLSON ET AL 2,562,635

ESCAPEMENT MECHANISM Filed 001;. 16, 1944 END OF RESET FIG-3.4-

IMPuLsE COMPLETED F16. 3

IMPULSE FIGZ DEAD BEAT FIG. I

INVENTORS a. 5 N/CHOL so/v BY J. a. MC GAY Patented July 31, 1951ESCAPEMENT MECHANISM George E. Nicholson and John B. McGay, Tulsa,Okla., assignors to Precision Products, Inc., Tulsa, Okla., acorporation of Oklahoma Application October 16, 1944, Serial No. 558,894

1 Claim. E

rotation.

Another object of this invention is to provide an escapement mechanismfor accurately governing a timer movement which is transmitting anexcessively high power which can be utilized for other purposes andstill not cause over-banking of the balance wheel in the escapementmechanism.

And still another object of this invention is to provide an escapementmechanism of the above nature wherein there is a simple self-startingarrangement that eliminates all friction or drag against the balancestaff of the mechanism.

A further object of this invention is to provide an escapement mechanismwhich is simple in construction, inexpensive in manufacture, eflicientand durable in use.

With these and other objects in view there has been illustrated on theaccompanying drawing, one form in which the invention may beconveniently embodied in practice.

Fig. 1 is an enlarged plan in showing the escapement mechanism in deadbeat position.

Fig. 2 is a similar view showing the mechanism in impulse position.

Fig. 3 is a similar view to Fig. 1 showing with the impulse completed.

Fig. 4 is also a similar view showing the mechanism at the end of itsreset position.

Fig. 5 is an enlarged fragmentary sectional elevational view of theescapement mechanism.

Referring to the drawing in detail wherein like reference charactersdenote corresponding parts throughout the various views, the numeral l0indicates a balance wheel rigidly mounted on a shaft l2 floatinglydisposed in bearings l4 and 16 secured in spaced clock plates l8 and 26.As disclosed in Fig. 5, a stud 22 is secured in plate I 8 and isprovided with a hair spring 24 connected to the balance wheel shaft l2.It is to be noted that the shaft 12 has a cutaway portion 26 forcooperating with the escapement lever which will hereinafter be referredto. An escapament lever 28 is pivoted on a shaft 3!! fixed between theplates l8 and 20. An escapement wheel 32 is fixed to a main shaft 34 inturn fixed between the plates l8 and 20. The escapement wheel isprovided with a plurality of peripheral teeth 36, each of which isconstructed so as to provide straight flat face 38 and an angular face40.

The escapement lever 28 is provided with a substantially circularcentral portion 42 having extending legs 44 and 46. The leg 44 has anapertured anchor 48 provided with extending legs 50 and 52. The leg 50has a projection or pallet 54 acting as the discharging end and isprovided with an angled or inclined front face 56 which will hereinafterbe described. Similarly leg 52 has a projection or pallet 58 acting asthe receiving end, however, no angled face is provided as in 54. Acounterweight 60 is disposed adjacent anchor 48. The end of leg 46 isprovided with a pair of prongs 62 and 64 having a recess or slot 66adapted to cooperate with a roller pin 68 provided on a strut 10 of thebalance wheel I0.

In operation, the escapement shaft 34 and wheel 32 are adapted toreceive power from a main spring of a clock works (not shown). From Fig.1 it is to be noted that the hair spring 24 has oscillated the balancewheel to a dead beat position wherein the roller pin 68 is in alignmentwith the center of the anchor 48 and the balance staff pin i2. Withpower applied to the escapement wheel 32, a tooth thereof is broughtinto contact with the angular face 56 of the pallet 54, thereby causingoscillation of the anchor 48 to provide a swinging movement of the lever28 in a counterclockwise direction according to Fig. l. Counterclockwisemovement of the lever causes the prong B2 to contact the roller pin 68and provide a clockwise rotation of the balance wheel Ill. The cutawayportion 26 allows for movement at the prongs 62 and 64 through the shaftl2. The angular face 56 of the pallet 54 provides for a simpleself-starting arrangement of the mechanism as will be hereinafterexplained. With the anchor 48 and lever 28 moving counterclockwise, thereceiving pallet 58 provided is placed in a position to contact a tooth35 of the escapement wheel 32, however, on the return of the balancewheel H) by the counterforce of the hair spring 24, the escapement leveris moved to the right or clockwise according to Fig. 2, thereby removingthe receiving pallet 58 out of contact with the teeth 36 to bring theescapement mechanism to an impulse position as 3 shown in Fig. 2. Inthis position a tooth 36 of wheel 32 is brought into direct contact withthe roller pin 65 on the balance wheel ID to cause a counterclockwiserotation (as shown in Fig. 2) of the balance wheel against the action ofthe hair spring 24.

Alluding to the self-starting feature, practically all priorself-starting escapement mechanisms are so constructed that there is adrag, or friction, against the balance staff, especially where theapplication of power is directed through an escapement lever to thebalance wheel. This is caused where the teeth of the escapement wheelare provided with apower or lift angle and bearing against the leverdirects thi power through the escapement lever against the balancestaff. The present structure precludes thi possibility because there isa positive look provided between the escapement teeth 36 and thedischarging and receiving pallets. The teeth 35 and the pallets 54 and58 are not provided with a power or lift angle. The inclined or angledend portion 56 of the pallet as mainly facilitates a self-startingarrangement of the mechanism from a dead beat position as shown Fig. 1,instantaneous as power is applied to the escapement wheel. In anyposition other than dead beat (Fig. l), the escapement wheel is eithermoving so as to bear against pin Bil, or is positively locked by eitherthe I receiving or discharging pallets. The angled face 5% has a veryslight impulse effect in a clockwise direction on the balance wheel.

With the impulse completed as shown in Fig. it is to benoted that theroller pin as has been moved out of the recess 66 and away from a toothof the wheel 25, thereby placing the discharging pallet in a lockedposition with a tooth 36 of the wheel At the completion of the impulse,the counterforce of the hair spring rotates the balance wheel in in aclockwise direction according to Fig. 4 to move pin 68 into the slot 66and cause movement of the escapement lever in a counterclockwisedirection according to Fig. 4, and bring the dischargin face 5 5 out ofcontact with a tooth and placing the receiving face 58 into contact withtooth E5. The operation continues as long as power is applied to theescapement wheel.

In the present invention the application of power from the escapementwheel directly to the roller pin of the balance wheel to cause rotationthereof, has the advantage over conventional escapement mechanisms ofsubstantially lessening friction on two normally longer lifting faces ofthe pallets thereof, thereby providing a more ef- 1 ficient operation bythe utilization of less torque. In the present mechanism, the speed ofoscillation oi the balance wheel, compared to the power and mas of theescapement wheel, tends to limit effectual operation of the balancewheel. Powerbeing applied to the escapement wheel of a certain mass, itfollows that it has a certain moment of inertia, and with the balancewheel oscillating at a definite rate of angular velocity as it passesits neutral or dead-beat position, then an equilibrium between theescapement wheel and the balance wheel is reached whenever the power tothe escapement wheel is not sufficient to raise the attained angularvelocity of the escapement wheel up to or beyond the attained angularvelocity of the balance wheel as the balance wheel passes its neutralposition. When this point of equilibrium is reached, there ceases anyflow of power from the escapement wheel to balance wheel through pin 68until the rate of angular velocity or" the balance wheel has decreased.In the present structure, the escapement wheel in moving through itsimpulse, transmits power to the roller pin 68 only when the angularvelocity of the roller pin on the balance wheel is less than theattained angular velocity of the escapement wheel. By this arrangement,a wide range of power can be applied to an escapement wheel of a certainmass without causing the balance wheel to oscillate beyond it limits oroverloanking, thereby, preventing a timing mechanism from keepingcorrect time. Furthermore, the additional power provided in theescapement wheel can be utilized for other purposes such as a resettingmechanism in a clock meter and still not cause overloanking of thebalance wheel when such additional power is not being used.

From the foregoing, it will be apparent that the present inventionpermits the use of escapement mechanism to govern the accurate runningof heavy duty clocks, and furthermore can be readily utilized in foreconomical timing devices which are prone to cease running when becomingslightly dirty due to the close ratio of spring power to the escapementwheel. The present high power escapement mechanism would keep this typeof time mechanism running irrespective of a small amount of debris andthe like. Furthermore, the temperature changes in cheaper timemechanisms affect the lubrication oil and sometimes cause themto stop,and use of the present high power escapement mechanism would precludethis detriment.

Changes may be made in the specification and drawings without departingfrom the spirit of the invention within the scope of the following claimas set forth.

We claim:

In an escapement mechanism having a power driven toothed escapementwheel, a balance wheel having a roller pin directly engaged by the teethof the escapement wheel, an escapement lever having a pair of pallets,one of said pallets having an inclined face, a tooth of the escapementwheel disposed in contact with the approximate center of the inclinedface at the instant the balance wheel oscillates past the neutralposition in a clockwise direction, a forked portion on the escapementlever contacting the roller pin, saidv forked portion and a tooth of theescape wheel both acting on the roller pin at the same distance from theaxis of the balance wheel.

GEORGE E. NICHOLSON. J GEN l3. MCGAY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain May 28, 1897

